David_Roveno
Posts: 5
Joined: Fri Mar 20, 2020 11:55 pm

Network Audio System

Sat Mar 21, 2020 1:04 am

Hello,

I'm looking for some advice & direction on a project I'm considering trying using a pair of Raspberry Pi's:

In brief, I'd like to (A) sample four separate analog audio channels from the output of a preamp receiver, transmit that across a LAN (preferably using Ethernet), and then (B) at another location receive the data and convert it back to four analog signals - all at 44.1 kHz, 16 bit quality, or so. This would be for the purpose of setting up a multi-zone home audio system.

Apparently there is hardware available that can do (A): HiFiBerry has a DAC/ADC board to which you can connect a second add-on board that provides four input channels:

https://www.hifiberry.com/shop/boards/d ... r-dac-dsp/

I did find some other audio I/O equipment at audioinjector.net that apparently can do (A) and (B) on one device, but the reviews on Amazon are not very encouraging.

Other than above I haven't found hardware that can "elegantly" do (B) - i.e., output four separate analog channels from a single Raspberry Pi.

Questions...

1. I have a fair bit of different coding experience, but have not used Linux much and don't have many hours to spend learning a new OS, etc. I also don't particularly enjoy working on networking! Are there any existing high-level configurable applications for the Pi that can do most/all or what I need?

2. Any better hardware recommendations for this project than what I've mentioned?

Many thanks!
~David.

PhatFil
Posts: 1640
Joined: Thu Apr 13, 2017 3:55 pm
Location: Oxford UK

Re: Network Audio System

Sat Mar 21, 2020 1:32 am

Im probably missing something here but it sounds like you just want to stream 4 x audio channels concurrently.

a google for "lightweight audio streaming pi"

pointed here viewtopic.php?t=202051

if 'lightweight' isnt an issue the heavyweights like vlc should also work..

David_Roveno
Posts: 5
Joined: Fri Mar 20, 2020 11:55 pm

Re: Network Audio System

Sat Mar 21, 2020 7:40 pm

Hi 'Fil,

I'll use a couple of pics to try to explain what I want to do. If I could, I would simply connect my existing AV receiver pre-amp outputs directly to some power amps as shown using plain old unbalanced RCA cables:

https://1drv.ms/u/s!AiK6l44c7PBLgZ4Krcu ... g?e=91ZeA3
(sorry, the "Insert Image" here doesn't work with a pic on Google Photos or OneDrive...)

Unfortunately I can't do that because the receiver and amp(s) are in different rooms. I've looked at using a different type of audio player, but most of them don't have multi-zone capabilities (and/or are very expensive if they do.)

So, the best alternative I can see is to do something like I've shown in the pic below, using a couple of Pi's:

https://1drv.ms/u/s!AiK6l44c7PBLgZ4J57w ... w?e=IDqW36

Hope that helps...
~David.

epoch1970
Posts: 4771
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: Network Audio System

Sat Mar 21, 2020 7:54 pm

Have you tried Logitech Media Server and friends?
http://forums.slimdevices.com
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

David_Roveno
Posts: 5
Joined: Fri Mar 20, 2020 11:55 pm

Re: Network Audio System

Sat Mar 21, 2020 9:51 pm

epoch1970 wrote:
Sat Mar 21, 2020 7:54 pm
Have you tried Logitech Media Server and friends?
http://forums.slimdevices.com
Okay - I've taken a look at that as a stand-alone media server, but it isn't clear how Spotify will work with Logitech/squeezebox. I prefer using Spotify Connect from my PC or iPad, whereas some media servers require a separate instance of Spotify to be running on the server (I think that may be how LMS works - if it does work with Spotify).

I like the way my receiver's iPad and iPhone apps work, etc., so prefer to try and that method I outlined work so that it can play in other zones.

...or are you suggesting that LMS can somehow do that?

epoch1970
Posts: 4771
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: Network Audio System

Sat Mar 21, 2020 11:04 pm

I was merely reacting to that:
David_Roveno wrote:
Sat Mar 21, 2020 7:40 pm
I've looked at using a different type of audio player, but most of them don't have multi-zone capabilities (and/or are very expensive if they do.)
LMS is server-centric, a good way to sync well with thin clients. There is a spotify plugin for the server, for example.
Some people seem to use it in "multi-zone" setup, but most would deploy networking, install players and then run synced groups. Multi-zone à la carte.
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

David_Roveno
Posts: 5
Joined: Fri Mar 20, 2020 11:55 pm

Re: Network Audio System

Sun Mar 22, 2020 2:08 am

epoch1970 wrote:
Sat Mar 21, 2020 11:04 pm
I was merely reacting to that:
David_Roveno wrote:
Sat Mar 21, 2020 7:40 pm
I've looked at using a different type of audio player, but most of them don't have multi-zone capabilities (and/or are very expensive if they do.)
LMS is server-centric, a good way to sync well with thin clients. There is a spotify plugin for the server, for example.
Some people seem to use it in "multi-zone" setup, but most would deploy networking, install players and then run synced groups. Multi-zone à la carte.
Thanks for your advice. Maybe something like that would be a more sensible approach. My idea seems simple in principle, but it might end up being a difficult project.

I did find some hardware on Alibaba that might have work it was available, but apparently it wasn`t a big seller:
https://www.aliexpress.com/item/1713489587.html

A bit more searching around revealed an earlier post here that was somewhat along the lines of mine:
viewtopic.php?t=227861
In that thread '6by9' chimed in about some of the technical challenges, which makes me think it would be not be a small/quick project.

epoch1970
Posts: 4771
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: Network Audio System

Sun Mar 22, 2020 11:08 am

I don't know anything about the AoE stuff but in general I think using ethernet in the same way you'd use dedicated audio cabling isn't advantageous.
The beauty of ethernet (or wifi, when it works) + TCP/IP is that it is a transport network, an infrastructure than can serve any purpose.

I read your initial post again. This is how it would be done using LMS, I think:
0 - Have a good local network, ethernet is always the best choice if possible. Flat ethernet cables do exist.
1 - Get a Pi3 or 4. Find a Hat that can manage 4 inputs (or get 4 USB inputs), have these 4 digital streams sent to LMS installed on the Pi. (I think co-location is best for AQ/status feedback, but some people have LMS receive "digital radio" streams from remote inputs.)
2 - Get X more Pis, with analogue out, a DAC Hat, or an amplifier Hat. Typically outputting stereo channels. Install player software on them, typically picorePlayer.
3 - Use the LMS web interface to group players and make groups play one of the 4 sources over the network.

The 1st item is already a bit unusual in the LMS world. More common is the addition of a single input stream, e.g. from a CD player or a turntable; but even this is not a popular use-case. It works, but it isn't end-to-end digital, so less practical/common.

Items 2 and 3 are the way I would do it. If you go to the forums you can find people having something like 6 USB DACs connected to one Pi, running 6 instances of player software. LMS sees 6 independent "zones", never syncs them. Doesn't make any sense to me, but it does exist.
On a good ethernet network, with slimdevices hardware players, you could sync 2 players, have one only render the left channel, the other only the right channel, have the 2 audio speakers centimeters away from each other, and never, ever notice anything wrong.
With the "dedicated software players" we now have, I'm not sure I would try that, but 1 m. away will feel perfect (shoddy network aside.)
This to say that I don't think using a single receiver is a great idea. Using a single sender, LMS, "guarantees" good sync, and I can surely live with that.

If you have a little bit of time, and 1 or more Pis at hand, I would suggest you try picoreplayer. It has a web interface, it serves as a player (its original intent) but it can also host the LMS server (+player if you want.) You can be up and running relatively quickly and get a feel for the server.
Then install a second Pi or install LMS on a VM, a laptop or something, and repurpose the Pi as player. You'll see how it works end-to-end.
To test sync, I would advise to use the same hw/sw combination on all players, so one more Pi would be necessary.
People say that LMS sync is good up to 50 players or something like that. I know a group of 10 is no problem at all, over a non-dedicated network.

HTH
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

David_Roveno
Posts: 5
Joined: Fri Mar 20, 2020 11:55 pm

Re: Network Audio System

Sun Mar 22, 2020 6:32 pm

epoch1970 wrote:
Sun Mar 22, 2020 11:08 am
I don't know anything about the AoE stuff but in general I think using ethernet in the same way you'd use dedicated audio cabling isn't advantageous.
The beauty of ethernet (or wifi, when it works) + TCP/IP is that it is a transport network, an infrastructure than can serve any purpose.

I read your initial post again. This is how it would be done using LMS, I think:
0 - Have a good local network, ethernet is always the best choice if possible. Flat ethernet cables do exist.
1 - Get a Pi3 or 4. Find a Hat that can manage 4 inputs (or get 4 USB inputs), have these 4 digital streams sent to LMS installed on the Pi. (I think co-location is best for AQ/status feedback, but some people have LMS receive "digital radio" streams from remote inputs.)
2 - Get X more Pis, with analogue out, a DAC Hat, or an amplifier Hat. Typically outputting stereo channels. Install player software on them, typically picorePlayer.
3 - Use the LMS web interface to group players and make groups play one of the 4 sources over the network.

The 1st item is already a bit unusual in the LMS world. More common is the addition of a single input stream, e.g. from a CD player or a turntable; but even this is not a popular use-case. It works, but it isn't end-to-end digital, so less practical/common.

Items 2 and 3 are the way I would do it. If you go to the forums you can find people having something like 6 USB DACs connected to one Pi, running 6 instances of player software. LMS sees 6 independent "zones", never syncs them. Doesn't make any sense to me, but it does exist.
On a good ethernet network, with slimdevices hardware players, you could sync 2 players, have one only render the left channel, the other only the right channel, have the 2 audio speakers centimeters away from each other, and never, ever notice anything wrong.
With the "dedicated software players" we now have, I'm not sure I would try that, but 1 m. away will feel perfect (shoddy network aside.)
This to say that I don't think using a single receiver is a great idea. Using a single sender, LMS, "guarantees" good sync, and I can surely live with that.

If you have a little bit of time, and 1 or more Pis at hand, I would suggest you try picoreplayer. It has a web interface, it serves as a player (its original intent) but it can also host the LMS server (+player if you want.) You can be up and running relatively quickly and get a feel for the server.
Then install a second Pi or install LMS on a VM, a laptop or something, and repurpose the Pi as player. You'll see how it works end-to-end.
To test sync, I would advise to use the same hw/sw combination on all players, so one more Pi would be necessary.
People say that LMS sync is good up to 50 players or something like that. I know a group of 10 is no problem at all, over a non-dedicated network.

HTH
Thank you for this. I think I'll get an audio/DAC HAT (and a Raspberry Pi) and give LMS a try...

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